High Resolution Laser Self-Mixing Displacement Sensor Under Large Variation in Optical Feedback and Speckle

Abstract

Self-Mixing interferometry (SMI) signal characteristics are highly dependent on both the operating optical regime and target surface. In this paper, a method is proposed to overcome some identified limitations of the even power scalable algorithm (EPSA) [1], such as the required operating regime to be weak feedback. In addition, by using the up-sampling techniques, the number of stages involved in the even-power scalable algorithm can be drastically increased without any data acquisition bandwidth modification. Here, 10 successive stages have been successfully implemented to achieve a theoretical resolution of λ0/2 13. It is further shown that the proposed method can handle and process weak, moderate and strong feedback regime as well as speckle affected SMI signals more efficiently. Lastly, FPGA based hardware emulation of EPSA is also done for later embedded implementation of this high-resolution algorithm. FPGA synthesis results show that the designed system can measure maximum target velocity up to 1.18 m/s while consuming total power of 1.4W.

Phase-unwrapping algorithm combined with wavelet transform and Hilbert transform in self-mixing interference for individual microscale particle detection

“…Besides measuring temporal signal waveform fringe number [18] and frequency spectral width [7] , novel precise alternatives for particle detection are still required. As a kind of phase observation tool, the phase-unwrapping method (PUM) has been exhaustively studied in SMI sensor systems [19][20][21][22][23][24][25][26][27] , and the spatial resolution even can reach λ=67 [28] . This processing method normally involves two steps: the first step is phase retrieval, and the second step is to estimate the feedback factor and linewidth enhancement factor for phase profile correction and displacement reconstruction.…”

A Self‐Decoupled and High‐Resolution 2D Displacement Sensor Based on Triboelectric Nanogenerator for Manipulator Precision Positioning

“…[6] At present, commercial displacement sensor principle can be broadly classified into several types, such as capacitive, inductive, piezoresistive, piezoelectric, and laser. [7][8][9][10] However, the low-frequency response of the inductive sensors cannot meet the requirement of fast dynamic measurements. And for the capacitive and piezoresistive sensors, they need an external power source to function, restricting the working life and challenging the miniaturization and portability of electronic devices.…”

Laser Self-Mixing Interferometer Based on Multiple Reflections and Phase-Modulation Technique

“…However, it is invalid when the amplitude of the target is much less than λ/2. In 2020, Amin et al [16] improved the even-power fast algorithm to deal with SMI signals with various optical feedback intensity regimes, including weak, moderate, and strong feedback, and speckle-affected. Besides these, several methods combining optical path improvement with algorithms have also been presented.…”